Present day implantation of artificial materials that contact blood is a frequent medical occurrence despite the paucity of knowledge concerning the biochemical and biophysical interactions of foreign surfaces with blood. The development of prosthetic devices which must contact blood is limited by the reactions which promote thrombogenesis. The platelet--a major blood reactant activated by any non-endothelial surface--may be retained or returned to the circulation in an altered state. During this process, the platelet may accelerate coagulation factor activation and promote thrombosis. None of these altered platelet states is desirable. There is a considerable amount of evidence to suggest that platelet activation can be modified by fatty acids in their environment. We propose to determine which of the fatty acids contained within albumin and adsorbed to a foreign surface can minimize platelet activation. Using techniques derived from column chromatography, relatively small volumes of blood will be passed over chemically highly purified small beads with a collectively large surface area. Aliquots of the column eluates will be tested for changes in platelets and coagulation factors. In addition, the beads will be examined by scanning electron microscopy for the quality of platelet retention (adhesion and/or aggregation). Those albumin variants which appear to be most thromboresistant will be used in an established, sensitive, continuously monitored ex vivo goat model for testing thrombogenecity.